A computer keyboard is a peripheral modeled after the typewriter keyboard. Keyboards are used to provide textual input into the computer and to control the operation of the computer. Physically, computer keyboards are generally an arrangement of rectangular or near-rectangular buttons or “keys,” which typically have engraved or printed characters. In most cases, each depressing of a key corresponds to a single character. However, some characters require that a user depress and hold several keys concurrently or in sequence. Depressing and holding several keys concurrently or in sequence can also result in a command being issued that affects the operation of the computer, or the keyboard itself.
There are several types of keyboards, usually differentiated by the switch technology employed in their operation. The choice of switch technology can affect the keys' response (i.e., the positive feedback that a key has been depressed) and travel (i.e., the distance needed to push the key to enter a character reliably). One of the most common keyboard types is a “dome-switch” keyboard which works as follows. When a key is depressed, the key pushes down on a rubber dome sitting beneath the key. The rubber dome collapses, which gives tactile feedback to the user depressing the key, and causes a conductive contact on the underside of the dome to touch a pair of conductive lines on a Printed Circuit Board (PCB) below the dome, thereby closing the switch. A chip in the keyboard emits a scanning signal along the pairs of lines on the PCB to all the keys. When the signal in one pair of the lines changes due to the contact, the chip generates a code corresponding to the key connected to that pair of lines. This code is sent to the computer either through a keyboard cable or over a wireless connection, where it is received and decoded into the appropriate key. The computer then decides what to do on the basis of the key depressed, such as display a character on the screen or perform some action. Other types of keyboards operate in a similar manner, with the main differences being how the individual key switches work. Some examples of other keyboards include capacitive-switch keyboards, mechanical-switch keyboards, Hall-effect keyboards, membrane keyboards, roll-up keyboards, and so on.
Conventional mechanical keyboards are generally accepted as the preferred means to provide textual input. These keyboards have mechanical keys that are configured to move independently of one another and comply with standards for key spacing and actuation force. These keyboards are also arranged in the so-called QWERTY layout. Over the last forty years there have been numerous attempts made to introduce an alternative to the standard keyboard. The changes include, but are not limited to, non-QWERTY layouts, concave and convex surfaces, capacitive keys, split designs, membrane keys, etc. However, although such alternative keyboards may provide improved usability or ergonomics, they have failed to replace or duplicate the commercial success of the conventional mechanical keyboard.